Multiple choice

The series given below has one wrong number find that number and answer the question. 0, 1, 9, 36, 99, 225, 441

  1. 225

  2. 441

  3. 99

  4. 36

  5. 9
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C Correct answer
Explanation

The pattern is squares of triangular numbers: 0², 1², 3², 6², 10², 15², 21² which gives 0, 1, 9, 36, 100, 225, 441. The base numbers (0, 1, 3, 6, 10, 15, 21) are triangular numbers. At position 5, we should see 100 but the series shows 99, making it the wrong number.

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